Zinc ion battery electrolyte containing phycocyanin as well as preparation method and application of zinc ion battery electrolyte

Abstract

The invention discloses a zinc ion battery electrolyte containing phycocyanin as well as a preparation method and application of the zinc ion battery electrolyte. The zinc ion battery electrolyte is prepared from soluble zinc salt, phycocyanin and water, wherein the concentration of the phycocyanin is 0.1 mmol / L to 0.5 mmol / L; the concentration of the soluble zinc salt is 1 mol / L to 2 mol / L. In the zinc ion battery electrolyte disclosed by the invention, phycocyanin is a natural biomacromolecule which is natural, non-toxic, low in cost and environment-friendly, has various structures and is rich in various active functional groups, and the problems of high toxicity, single function, poor economic benefit and high cost of an organic additive in the prior art are solved. Besides, the zinc ion battery electrolyte can inhibit dendritic crystal growth, a stable interface layer is formed on the surface of a zinc negative electrode, side reactions are reduced, and the cycling stability and coulombic efficiency of the battery are improved.

Description

Technical Field

[0001] This invention relates to the field of electrochemical technology, and more specifically to a zinc-ion battery electrolyte containing phycocyanin, its preparation method, and its application. Background Technology

[0002] Zinc-ion batteries, as an electrochemical energy storage system with zinc metal as the negative electrode and aqueous electrolyte as the basis, have shown broad application prospects in the fields of large-scale energy storage and flexible electronic devices due to their advantages such as high safety, low cost, environmental friendliness and abundant resources.

[0003] However, the inherent stability of zinc anodes in aqueous electrolytes severely restricts their practical application. These problems mainly manifest in two aspects: First, during battery cycling, zinc ions tend to deposit non-uniformly on the anode surface, forming zinc dendrites. The growth of dendrites can puncture the separator, leading to internal short circuits in the battery, posing serious safety hazards, and significantly shortening the battery cycle life. Second, the thermodynamic instability of zinc metal makes it highly susceptible to hydrogen evolution reaction with water molecules in the electrolyte, generating inert byproducts (such as basic zinc sulfate Zn4SO4(OH)6·xH2O) in the near-surface region, leading to irreversible corrosion, passivation, and capacity decay of the zinc anode.

[0004] To address the aforementioned issues, introducing functional additives into the electrolyte has become a simple and effective strategy. Currently, the most studied additives mainly include: 1) small organic molecules (such as alcohols and ethers), which have limited functions, rely primarily on physical adsorption, and may reduce electrolyte stability; 2) synthetic polymers (such as polyvinylpyrrolidone), which, while effective, are typically complex to synthesize and costly; and 3) some nitrogen-containing organic compounds (such as amides and amines), which exhibit certain biotoxicity, contradicting environmental friendliness principles and potentially introducing new side reactions. Existing additive systems generally suffer from drawbacks such as limited functionality, high cost, environmental unfriendliness, or complex synthesis processes, making it difficult to achieve an effective balance between inhibiting dendrite growth and mitigating side reactions (especially hydrogen evolution reaction). Therefore, developing a green, low-cost, multifunctional, and synergistic novel electrolyte additive is crucial for promoting the development of high-performance aqueous zinc-ion batteries. Summary of the Invention

[0005] In view of this, and addressing the shortcomings of existing electrolyte additives in terms of toxicity, cost, functionality, and environmental friendliness, this invention provides a zinc-ion battery electrolyte containing phycocyanin and its preparation method. This electrolyte uses phycocyanin as a functional additive, leveraging its unique molecular structure to simultaneously achieve multiple functions such as regulating the zinc ion solvation structure, inhibiting zinc dendrite growth, and reducing side reactions, thereby producing a high-performance, long-life, and environmentally friendly aqueous zinc-ion battery. The phycocyanin molecular structure contains polar functional groups such as amide, carboxyl, and porphyrin rings, which can react with Zn... 2+ Ion complexation effectively regulates its solvation structure and promotes its uniform deposition on the zinc anode surface, thereby inhibiting the formation of zinc dendrites. At the same time, phycocyanin can adsorb on the zinc metal surface to form a stable interface layer, preventing direct contact between highly active water molecules in the electrolyte and metallic zinc, reducing the frequency of hydrogen evolution reaction, reducing the generation of inactive byproducts, improving the electrochemical activity and stability of the zinc anode, and overcoming the technical defects of existing electrolyte additives.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] First, this invention provides a zinc-ion battery electrolyte containing phycocyanin, using water as a matrix, comprising 0.1 mmol / L to 0.5 mmol / L of phycocyanin and 1 mol / L to 2 mol / L of soluble zinc salt. Note that excessively high or low concentrations of phycocyanin can affect the solvation structure of zinc ions, leading to a decrease in their application performance.

[0008] Preferably, the concentration of phycocyanin is 0.2 mmol / L, and the concentration of soluble zinc salt is 2 mol / L.

[0009] Preferably, the soluble zinc salt is zinc sulfate, zinc nitrate, or zinc chloride.

[0010] This invention also provides a method for preparing the zinc-ion battery electrolyte containing phycocyanin as described above, comprising the following steps:

[0011] Soluble zinc salts and phycocyanin are dissolved together in water to obtain a zinc-ion battery electrolyte containing phycocyanin.

[0012] The present invention also provides an application of the zinc-ion battery electrolyte containing phycocyanin as described above in the preparation of zinc-ion batteries.

[0013] Furthermore, the zinc-ion battery includes a zinc-ion battery electrolyte containing phycocyanin, a positive electrode, a negative electrode, and a separator.

[0014] Furthermore, the zinc-ion battery is a zinc-zinc symmetric battery, operating at 2 mA / cm². 2During constant current charge-discharge testing at current density, the cycle life is no less than 5400 hours, and the overpotential is always below 60mV.

[0015] As can be seen from the above technical solution, compared with the prior art, the present invention discloses a zinc-ion battery electrolyte containing phycocyanin, its preparation method and application, which has the following beneficial effects:

[0016] Most additives in existing technologies have only one function and are difficult to simultaneously regulate Zn. 2+ To address the issues of solubilizing the structure and protecting the zinc interface, this invention introduces phycocyanin as a functional organic additive, which can effectively improve the electrochemical stability of the zinc anode, significantly inhibit the growth of zinc dendrites, reduce side reactions at the electrolyte-zinc anode interface, and enhance the reversibility of zinc anode deposition and stripping, thereby overcoming the limitations of existing additives that lack multiple functionalities.

[0017] Compared with commonly used organic additives in existing technologies, such as N-methylformamide and triethanolamine, phycocyanin has the advantages of being natural and non-toxic, low-cost, environmentally friendly, structurally diverse, and containing multiple active functional groups. It overcomes the shortcomings of existing additives, such as high toxicity, limited functionality, and high cost, and has greater application and promotion value. Furthermore, the zinc-ion battery electrolyte provided by this invention significantly improves the cycle stability of the zinc anode, coulombic efficiency, and overall battery life, making it suitable for constructing next-generation green, safe, and high-performance aqueous zinc-ion batteries, and showing promising practical application prospects.

[0018] The phycocyanin molecule used in this invention contains amide, carboxyl, and porphyrin ring functional groups simultaneously. These amide, carboxyl, and porphyrin ring functional groups can interact with Zn. 2+ Ions interact and change Zn 2+ The surrounding solvation environment modulates Zn 2+ The deposition behavior of phycocyanin allows it to be deposited more uniformly on the zinc anode surface, reducing the formation of zinc dendrites. Simultaneously, phycocyanin can also adsorb onto the zinc anode surface, forming a protective film that prevents highly reactive water molecules in the electrolyte from reacting with hydrated Zn. 2+ The ions come into direct contact with the zinc anode surface, thereby reducing the occurrence of hydrogen evolution reaction, inhibiting the formation of by-products, improving the electrochemical activity of the zinc anode, and extending the cycle life and coulombic efficiency of the zinc-ion battery.

[0019] The zinc-ion battery electrolyte of this invention can effectively improve the cycle stability of the zinc anode in zinc-ion batteries and can be applied to aqueous zinc-ion battery energy storage devices. Specifically, a zinc-symmetric battery using the zinc-ion battery electrolyte of this invention can cycle stably for 5400 hours, and the overpotential remains below 60mV throughout the cycle. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0021] Figure 1 SEM images of the Zn surface after immersion in the PC / ZnSO4 electrolyte of Example 1 and the ZnSO4 electrolyte of Comparative Example 1 for 10 days, respectively. Figure 1 Image (a) shows a SEM image of the Zn surface after immersion in ZnSO4 of Comparative Example 1 for 10 days. Figure 1 (b) is a SEM image of the Zn surface after immersion in PC / ZnSO4 in Example 1 for 10 days;

[0022] Figure 2 The CV curves of zinc-titanium batteries (Zn-Ti batteries) assembled with PC / ZnSO4 electrolytes in Examples 1, 2, and 3 and ZnSO4 electrolyte in Comparative Example 1 are shown.

[0023] Figure 3 The LSV curves of the PC / ZnSO4 electrolytes of Examples 1, 2, and 3 and the ZnSO4 electrolyte of Comparative Example 1 are shown in a three-electrode system with Zn foil as the working electrode, Pt mesh as the counter electrode, and Ag / AgCl electrode as the reference electrode.

[0024] Figure 4 Impedance diagrams of zinc-zinc symmetric cells, i.e., Zn||Zn symmetric cells, in the ZnSO4 electrolyte of Comparative Example 1 and the PC / ZnSO4 electrolyte of Example 1;

[0025] Figure 5 The diagram shows the long-cycle stability of the Zn||Zn symmetric battery in the ZnSO4 electrolyte of Comparative Example 1 and the PC / ZnSO4 electrolyte of Examples 1-3, along with the corresponding charge-discharge curves. The diagram also shows the charge-discharge curves of the Zn||Zn symmetric battery in the electrolyte of Example 1 for different cycles. Figure 5 (a) shows the long-cycle stability of the Zn||Zn symmetric battery in the ZnSO4 electrolyte of Comparative Example 1 and the PC / ZnSO4 electrolyte of Examples 1-3, along with the corresponding charge-discharge curves. Figure 5 (b) in the figure is the charge-discharge curve of the Zn||Zn symmetric battery after cycling in the electrolyte of Example 1 for 900h~905h. Figure 5 (c) in the figure is the charge-discharge curve of the Zn||Zn symmetric battery after cycling in the electrolyte of Example 1 for 3000h~3005h. Figure 5In the figure (d), the charge-discharge curve of the Zn||Zn symmetric battery after cycling in the electrolyte of Example 1 for 5000h~5005h is shown. Detailed Implementation

[0026] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0027] It should be noted that the technical terms used in this invention are for the purpose of describing specific embodiments only and are not intended to limit the scope of protection of this invention. Unless otherwise specified, all raw materials, reagents, instruments and equipment used in the following embodiments of this invention can be purchased through conventional commercial channels or prepared by existing methods. Phycocyanin is abbreviated as PC; zinc foil is abbreviated as Zn.

[0028] Example 1

[0029] A method for preparing a zinc-ion battery electrolyte includes the following steps:

[0030] Weigh 0.322 g of zinc sulfate and 0.117 mg of PC. Dissolve the zinc sulfate and PC in 1 mL of deionized water to obtain a zinc-ion battery electrolyte, denoted as PC / ZnSO4 electrolyte, or ZS / PC for short. The concentration of zinc sulfate is 2 mol / L, and the concentration of PC is 0.2 mmol / L.

[0031] Example 2

[0032] A method for preparing a zinc-ion battery electrolyte includes the following steps:

[0033] Weigh 0.322 g of zinc sulfate and 0.0586 mg of PC. Dissolve the zinc sulfate and PC in 1 mL of deionized water to obtain a zinc-ion battery electrolyte, denoted as PC / ZnSO4 electrolyte. The concentration of zinc sulfate is 2 mol / L, and the concentration of PC is 0.1 mmol / L.

[0034] Example 3

[0035] A method for preparing a zinc-ion battery electrolyte includes the following steps:

[0036] Weigh 0.322 g of zinc sulfate and 0.293 mg of PC. Dissolve the zinc sulfate and PC in 1 mL of deionized water to obtain a zinc-ion battery electrolyte, denoted as PC / ZnSO4 electrolyte. The concentration of zinc sulfate is 2 mol / L, and the concentration of PC is 0.5 mmol / L.

[0037] Example 4

[0038] A method for preparing a zinc-ion battery electrolyte includes the following steps:

[0039] Weigh 0.161 g of zinc sulfate and 0.117 mg of PC. Dissolve the zinc sulfate and PC in 1 mL of deionized water to obtain a zinc-ion battery electrolyte, denoted as PC / ZnSO4 electrolyte. The concentration of zinc sulfate is 1 mol / L, and the concentration of PC is 0.2 mmol / L.

[0040] Example 5

[0041] A method for preparing a zinc-ion battery electrolyte includes the following steps:

[0042] Weigh 0.1201 g of zinc sulfate and 0.117 mg of PC. Dissolve the zinc sulfate and PC in 1 mL of deionized water to obtain a zinc-ion battery electrolyte, denoted as PC / ZnSO4 electrolyte. The concentration of zinc sulfate is 1.5 mol / L and the concentration of PC is 0.2 mmol / L.

[0043] Comparative Example 1

[0044] A method for preparing an aqueous zinc-ion battery electrolyte includes the following steps:

[0045] 0.322 g of zinc sulfate was dissolved in 1 mL of deionized water to obtain an aqueous zinc-ion battery electrolyte, denoted as ZnSO4 electrolyte, or Pure ZS for short. The concentration of zinc sulfate was 2 mol / L.

[0046] Experimental Example

[0047] Commercially purchased zinc foil was immersed in the ZnSO4 electrolyte of Comparative Example 1 and the PC / ZnSO4 electrolyte of Example 1 for 10 days, and its performance was characterized and tested.

[0048] Depend on Figure 1 (a) and Figure 1 Figure (b) shows that the zinc foil surface after immersion in the ZnSO4 electrolyte of Comparative Example 1 was uneven and severely corroded. In contrast, the zinc foil surface immersed in the PC / ZnSO4 electrolyte of Example 1 remained smooth and flat.

[0049] Zn||Ti batteries assembled with the ZnSO4 electrolyte of Comparative Example 1 and the PC / ZnSO4 electrolyte of Examples 1, 2, and 3 were subjected to CV tests to evaluate the effect of PC additives on zinc nucleation and growth processes.

[0050] Depend on Figure 2 It was found that in the PC / ZnSO4 electrolytes of Examples 1, 2, and 3, the nucleation overpotential for zinc deposition gradually increased with increasing PC additive concentration. Furthermore, the nucleation overpotentials in Examples 1, 2, and 3 were all greater than that in Comparative Example 1. A larger nucleation overpotential is beneficial for the adsorbed PC to reduce the surface energy of the zinc anode / electrolyte interface, refine zinc grains, and make Zn deposition more uniform and dense. It also helps to effectively control the rapid zinc deposition process.

[0051] Using Zn foil as the working electrode, Pt mesh as the counter electrode, and Ag / AgCl electrode as the reference electrode, the LSV curves of the PC / ZnSO4 electrolytes of Examples 1, 2, and 3 and the ZnSO4 electrolyte of Comparative Example 1 were tested in a three-electrode system to further investigate the effect of PC on electrolyte stability.

[0052] observe Figure 3 It was found that at a current density of 10 mA / cm² 2 In Examples 1, 2, and 3, the hydrogen evolution overpotential of the electrolytes was higher than that of Comparative Example 1 (-1.08V). The most significant inhibitory effect on the hydrogen evolution reaction was observed when the PC concentration was 0.2 mM, with an overpotential of -1.12V. This indicates that the addition of PC not only facilitates the zinc deposition / stripping process but also effectively inhibits the occurrence of the hydrogen evolution reaction.

[0053] The PC / ZnSO4 electrolytes of Examples 1, 2 and 3 and the ZnSO4 electrolyte of Comparative Example 1 were used in zinc-zinc symmetric cells, i.e., Zn||Zn symmetric cells. After standing for 2 hours, the Zn||Zn symmetric cells with different electrolytes were subjected to EIS tests.

[0054] observe Figure 4 The results showed that the charge transfer impedance of the Zn||Zn symmetric cells using the PC / ZnSO4 electrolyte in Examples 1, 2, and 3 increased with increasing PC concentration. The charge transfer impedance of Examples 1 and 2 was lower than that of Comparative Example 1, while the charge transfer impedance of Example 3 was significantly higher than that of Comparative Example 1. The interfacial impedance of Examples 1, 2, and 3 was lower than that of Comparative Example 1, with the lowest interfacial impedance observed at a PC concentration of 0.2 mM. This indicates that the PC additive significantly improves the Zn||Zn symmetric cell charge transfer impedance. 2+ The transfer rate has a significant effect on promoting uniform zinc deposition.

[0055] The PC / ZnSO4 electrolyte of Comparative Example 1 and the ZnSO4 electrolytes of Examples 1, 2, and 3 were applied to zinc-zinc symmetric cells, i.e., Zn||Zn symmetric cells, using 2 mA / cm². 2 Constant current charge-discharge tests were performed using the current density, and the time-voltage curves were observed.

[0056] observe Figure 5 From (a) we get that at 2mA / cm 2 At the specified current density, the Zn||Zn symmetric cell assembled using the 2 mol / L ZnSO4 electrolyte of Comparative Example 1 could only cycle stably for 300 h. In contrast, the Zn||Zn symmetric cell using the PC / ZnSO4 electrolyte of Example 1 could cycle stably for 5400 h. Meanwhile, the Zn||Zn symmetric cell assembled using the PC / ZnSO4 electrolyte of Example 1 could cycle stably for 5400 h. Figure 5 (b) Figure 5 (c) Figure 5 The enlarged view of the charge-discharge curve in (d) shows that after 900h, 3000h and 5000h overpotential cycling of the symmetrical battery using the electrolyte of Example 1, the overpotential does not exceed 60mV.

[0057] The various embodiments described in this specification are presented in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A zinc-ion battery electrolyte containing phycocyanin, characterized in that, Using water as a matrix, it includes phycocyanin at concentrations of 0.1 mmol / L to 0.5 mmol / L and soluble zinc salts at concentrations of 1 mol / L to 2 mol / L.

2. The zinc-ion battery electrolyte containing phycocyanin according to claim 1, characterized in that, The concentration of phycocyanin is 0.2 mmol / L, and the concentration of soluble zinc salt is 2 mol / L.

3. A zinc-ion battery electrolyte containing phycocyanin according to claim 1 or 2, characterized in that, The soluble zinc salt is zinc sulfate, zinc nitrate, or zinc chloride.

4. A method for preparing the zinc-ion battery electrolyte containing phycocyanin as described in any one of claims 1-3, characterized in that, Includes the following steps: Soluble zinc salts and phycocyanin are dissolved together in water to obtain a zinc-ion battery electrolyte containing phycocyanin.

5. The application of the zinc-ion battery electrolyte containing phycocyanin as described in any one of claims 1-3 in the preparation of zinc-ion batteries.

6. The application according to claim 5, characterized in that, The zinc-ion battery includes a zinc-ion battery electrolyte containing phycocyanin, a positive electrode, a negative electrode, and a separator.

7. The application according to claim 5, characterized in that, The zinc-ion battery is a zinc-zinc symmetric battery, with a current of 2 mA / cm². 2 During constant current charge-discharge testing at current density, the cycle life is no less than 5400 hours, and the overpotential is always below 60mV.

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